We are trying to identify novel or known viruses as causes of diseases of uncertain etiology. Blood and tissues from patients are being examined by sensitive PCR tests in an attempt to find new or known viruses that are responsible for the diseases. Previously, we used these procedures to identify human herpesvirus 6 in lymph node biopsies from three patients who presented with fever and enlarged lymph nodes. Cytomegalovirus causes congenital disease which can result in deafness and mental retardation in neonates, and can cause severe viral pneumonia and colitis in transplant recipients and sight-threatening retinitis in patients with AIDS. Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with a number of cancers including Burkitt lymphoma, nasopharyngeal carcinoma, Hodgkins disease, and post-transplant lymphoproliferative disease. Human CMV and EBV infect humans, but not small animals or nonhuman primates. The best models currently available for CMV and EBV are rhesus monkey CMV and EBV. The goal of this study is to develop an effective vaccine for these rhesus viruses and to use these as a model for vaccines for their human counterparts. We are using various approaches including soluble recombinant proteins, recombinant virus vectors expressing viral proteins, and replication defective viruses as vaccines. We have collaborated with a laboratory at the Food and Drug Adminstration to try to detect viruses in clinical specimens using novel assays that do not depend on known virus sequences or antibodies. In 2009 we isolated DNA and RNA from bronchoalveolar lavage fluid in an immunocompromised patient suffering from pneumonia in whom a causative agent could not be identified by routine methods. cDNA was prepared from the RNA and the polymerase chain reaction was performed using degenerate oligonucleotide primers to amplify the DNA and the cDNA from the broncholalveolar lavage fluid. The PCR products were cloned and sequenced and human metapneumovirus was identified by sequence analysis. Therefore this procedure should be able to identify new viruses in clinical specimens. We are currently using this system to try to identify viruses in other clinical specimens in which an infectious microorganism has not been able to be identified.